A number of foamed glass products are generally known in the art. Foamed glass panels have been formed by blowing air or another gas into molten glass and allowing the molten glass to cool and entrap the bubbles or cells in the solidified glass. Alternatively, foamed glass has been formed by mixing a gas-generating agent, or foaming agent, with finely crushed glass particles. The mixture is then heated to a temperature at which the glass is sinterend, softened or molten and the foaming agent releases gases. The mixture is then cooled to entrap the bubbles or cells formed by the gases.
Foamed glass has a number of desirable characteristics that make it useful as an insulation product. For example, foamed glass insulation products are generally moisture resistant, fire resistant, corrosion resistant, and vermin resistant. However, foamed glass insulation products are not without problems. For example, lack of relative uniformity as to size, cell wall thickness, and cell distribution have had a negative impact on the quality and characteristics of foamed glass products. Also, foamed glass products have been expensive, and use of foamed glass has not been widespread due in part to its relatively modest insulative properties. Advertising for a common foamed glass product cites an R-value of 3.3 hr.multidot.ft.sup.2 .multidot..degree..multidot.F./Btu.multidot.in, which compares poorly with polyisocyanurate foam core insulating materials which, according to advertising materials, provide R-values of over 5.6 hr.multidot.ft.sup.2 .multidot..degree.F./Btu.multidot.in. Foamed glass insulation may nonetheless be preferable to polyisocyanurate panels because polyisocyanurate panels incorporate freon gas, a chloro- fluorocarbon (CFC) that can leak from the foam. Rigid foam polyurethane is also popular in building energy efficient housing but suffers from a similar problem in that CFCs and. hydrochloro-fluorocarbons (HCFCs) are released during production.
With respect to starting materials, commercially manufactured foamed glass typically uses virgin glass as starting materials. This is unfortunate in light of the desirability of finding new uses for scrap glass containers and mixed color cullett. Various glass recyclers are able to recycle much of the scrap glass containers collected in the U.S. However, glass breakage during collection creates a mixed color cullet fraction estimated at approximately 10% to 20% of the glass containers collected, and it is more difficult to find suitable uses for this mixed color cullet fraction.